Weather Talk: Cool weather, drought meant fewer tornadoes

Through April, only three people had died from tornadoes so far in 2013. In the very active tornado year of 2011, 543 deaths had already occurred by this date.

During the 12-month period ending in April, there have been just seven tornado deaths, the fewest in any

12-month period since the 12 months ending in August 1900.

There are two reasons for the absence of tornadoes. In 2013, the persistently cool temperatures east of the Rockies made the atmosphere too stable for tornadoes despite a number of vigorous storm systems. The other reason for the low count is the severe drought in the central United States last summer.

May is typically the stormiest month across the United States for tornadoes, but until Thursday, there had only been three so far this month, all of them rated as weak EF-0 twisters with winds less than 85 mph.

But on Wednesday, 10 tornadoes touched down in central Texas, including two very strong ones which caused considerable damage and several fatalities.